Laminitis, infection, and colic among threats for Kentucky Derby winner

by Denise Steffanus

FLAWLESS handling of events related to Barbaro's breakdown in the Preakness Stakes (G1) on May 20--from the quick response of jockey Edgar Prado in pulling up the colt before he caused himself further injury to the groundbreaking surgery by Dean Richardson, D.V.M., chief surgeon at the University of Pennsylvania's New Bolton Center, to the expert care the horse has received there--has created a best-case scenario for Barbaro's recovery. Yet, obstacles remain in his path:

•Potential to develop laminitis in the opposite hind foot;

•Chance of infection;

•Possibility of impaction colic from physical and mental stress;

•Reinjury because of the tendency of an ultra-fit horse to be too active while confined; and

•Unsatisfactory healing.

Laminitis threat

Perhaps the greatest fear surrounding Barbaro's recovery is that he will develop laminitis in his opposite hind foot as a result of a natural tendency to transfer weight bearing from the fractured limb onto the opposite one.

When a horse places weight on a foot, it registers a negative blood flow, actually forcing blood away from the coffin bone and through the back of the foot through tiny blood vessels called microvasculature. A horse with an orthopedic injury that spends too much time standing on the opposite leg causes the blood flow to diminish in that foot, which can lead to laminitis.

Ric Redden, D.V.M., possibly the world's most famous authority on laminitis, said careful and constant monitoring of Barbaro's left hind foot could enable surgeons to detect changes in blood flow early enough to intervene, should laminitis begin to develop. That monitoring could be done through radiographs that carefully measure soft-tissue parameters within a half-millimeter and venograms to assess blood supply to the foot. Additionally, Redden, who is based in Lawrenceburg, Kentucky, recommended the application of a special device to the sound foot that promotes a continued, good blood supply.

If this were one of his cases, Redden said he would begin by taking radiographs of Barbaro's left hind foot to establish a baseline for comparison with any changes that might begin to occur.

"The soft-tissue parameters I'm looking for are sole depth, plantar angle, and the horn-lamellar zone," he said. "These are basic parameters that I monitor constantly on the good foot for all high-risk patients. Knowing those parameters, I set the foot up in a device that will allow that foot to reach an adjustable 18¡ to 20¡ plantar angle."

The rocker device comprises a special shoe designed by Redden called the Modified Ultimate, two 5¡ wedges, and a cuff. It is either glued on or attached with a secure bandage.

"As it rocks forward, you decrease the tension on the deep digital flexor tendon to the point where you get about 60% to 70% tendon release, and that allows perfusion of blood to go under the bone into the sole corium, and it reduces a lot of the stress on the wall and the laminae," he said. "And that's the whole point: to enhance perfusion to the laminae and to the sole corium during the high-risk period, which is about six to eight weeks. With venograms, I can monitor how effective this device is by monitoring blood flow."

Redden has found venograms to be a useful tool to detect small changes in blood supply that may indicate the development of laminitis long before clinical signs are evident--an important factor because clinical signs are outward manifestations that laminitic damage already has occurred.

"The fortunate thing about it is the venogram will show me days to weeks before radiographs will show this horse has any sign of laminitis," Redden said. "I can see it in the venogram so clearly. It's a stark difference in where the blood flow was last week and where it is today.

"Most of these [post-surgical] horses stay very happy for four to five weeks, and then suddenly they're standing on the cast leg and the other foot's in the air. The laminitis has occurred about three or four weeks prior to that. So it's just a nice way for me to know where I am on a daily basis with the good foot."

If the venogram shows vascular changes, Redden said it is early enough to take measures to stop the progression of laminitis, and 95% of horses respond well when treated at this early stage, provided healing in the repaired limb is progressing satisfactorily.

Redden recommended performing radiographs and venograms about every ten to 15 days after surgery.

According to Redden, performing a venogram is a risky procedure that can damage blood flow to the limb if it is done incorrectly.

Slew's surgeon

Barrie Grant, D.V.M., M.S., chief of staff at San Luis Rey Equine Hospital in Bonsall, California, developed and performed the delicate surgeries on Triple Crown winner Seattle Slew's neck to relieve the neurological effects of impingement of the stallion's spinal cord from wobbler disease. Grant also pioneered the use of amputation and prosthetics to save the lives of horses with irreparable damage to a limb. The top-notch surgeon has been following Barbaro's progress, and he is guardedly optimistic about the colt's recovery.

"Trying to get all those pieces of the jigsaw put back together, you know, Humpty Dumpty ...," Grant said. "It looks like they did a pretty good job with what they had to work with."

According to Grant, infection is another major threat, but he believes New Bolton has that under control.

"[Barbaro] would have had a fever by now [three days after surgery]," Grant said of the possibility of infection. "They would have seen some early signs of it by now, but not necessarily; there are no absolutes. You still have to keep all your fingers and toes crossed, for sure."

Prado's ability to get Barbaro pulled up before he broke through the bandage he wore for the race was a key factor in minimizing infection.

According to Grant, impaction and possible rupture of the cecum, where the small and large colon join, constitute one of the leading causes of death in horses recovering from catastrophic injuries.

"The surgery, the painkillers, being a little dehydrated, and the stress could make the cecum become impacted," he said.

Grant added that he was confident New Bolton would be on top of that potential problem because Corinne Sweeney, D.V.M., the executive director of New Bolton's George Widener Hospital for Large Animals, is the leading researcher into how to prevent that complication from arising.

Barbaro's shattered ankle was repaired with 27 screws and a locking compression plate, which to the uneducated eye would seem to further traumatize the bones.

"I don't think it's that much of an insult [to the bones] compared with being fractured," Grant said. "You can have lots of metal in there, and it's not too big a problem initially. Sooner or later, if you don't start taking it out a little bit at a time, the bone doesn't respond and get strong because it's relying on the metal. They did a nice job and it's better to have one screw too many than one too few.

"You just kind of hope you're going to get a lot of osteoblasts [repair cells] in there to start taking over some of the strength that the bone plates lose," Grant said.

But as healing progresses and Barbaro must undergo more cast changes, radiographs, blood work, and other procedures, there is a danger he will become fed up with hospitalization and begin to fight his handlers. On the other hand, the Kentucky Derby (G1) winner may begin to feel so good that he will put more weight on his reconstructed limb than it can withstand at that point in healing. For both these scenarios, the crucial factor will be the horse's intelligence and the trust he develops in the New Bolton staff.

"It surprised me, actually, that the horse is allowing himself to be put in a sling because he looked so tough when he was being saddled [for the Preakness]," Grant said. "I was pretty impressed, really. But that's what they said about Seattle Slew, too, that you couldn't put a sling around him, and he ended up being just fine. He caught on, too. Those classy horses seem to know when they have to put up with things."

Enhanced healing

Doug Herthel, D.V.M., is the founder and chief of staff of Alamo Pintado Equine Medical Center in Los Olivos, California. Two areas that are his passion are nutritional support for the injured athlete and hyperbaric oxygen therapy. He typically combines both to benefit his post-operative equine patients. Nutritional support gives the horse's body the building blocks it needs to repair broken bones, and hyperbaric oxygen therapy reduces swelling, enhances blood flow, and fights infection.

"Omega-3 essential fatty acid decreases bone loss and stimulates bone healing," Herthel said. "Obviously, you are going to provide all the other bone factors: [vitamins] C, D, and K, boron, potassium, magnesium, and calcium. And then silicon is really important. Silicon promotes bone healing."

All these ingredients are found in a supplement Herthel developed, Platinum Performance. Another supplement he developed specifically for bone repair is Osteon.

"Osteon is a real-high silicon product," Herthel said. "The whole idea behind it is to increase bone density, and silicon has been shown to increase bone density."

When new bone forms, it begins by laying down a matrix of collagen and cartilage. During the process called ossification, cartilage incorporates calcium and other minerals that transform it into bone. Although the exact role of silicon is unclear, researchers believe it is a pivotal element in the formation of collagen and glycosaminoglycans, the major components of the bone matrix.

One of the first notable horses to benefit post-surgically from a regimen of Platinum Performance was 1996 Breeders' Cup Juvenile (G1) winner and champion two-year-old male Boston Harbor. The colt sustained a non-displaced condylar fracture while preparing for the 1997 Kentucky Derby. At Alamo Pintado, Herthel implanted screws to pull the fracture together and started the colt on the supplement. Less than two weeks later, Herthel reported that X-rays taken of the fracture revealed that fracture lines had totally disappeared.

Unfortunately for Barbaro, a key modality Herthel uses to enhance healing, hyperbaric oxygen therapy, is not available at New Bolton. A hyperbaric oxygen chamber costs  about $350,00.

While the horse stands comfortably in the sealed, pressurized chamber that resembles a space capsule, oxygen permeates its body to nourish areas where the blood supply may be less than optimum, such as Barbaro's reconstructed ankle, thereby accelerating healing.

"It enhances the ability of antibiotics to fight infection," Herthel said. "And when you raise the oxygen to 15 times normal, it has a stimulatory effect on new blood vessels, too. It also is used for treating osteomyelitis [bone infection], but, better yet, it can be used to prevent it.

"This hasn't been shown in horses yet," Herthel continued, "but in other animals and people, it has been shown that by alternating the pressures that the treatments are set at, you actually can stimulate osteoblastic activity, or bone-healing activity."

Denise Steffanus is a contributing editor of Thoroughbred Times who writes frequently on veterinary and farm management topics.